Those most vulnerable to coronavirus will only be recommended for immediate access to vaccines if the scientific data shows it works best for them, the head of the European Medicines Agency (EMA) has said.
"Our job is to look at the application and decide whether there is a positive benefit risk," the EMA executive director Emer Cooke told the Herald.
"We will outline the indication for the vaccines for the type of population it shows positive outcomes for.
"So if it's the elderly population, the paediatric population, or people with comorbidities, these are things we'll be looking at to see if there is sufficient data to support that in the dossier."
However, the final allocation and deployment of vaccines is decided at member-state level by a national immunisation committee, opening up the possibility that national governments could differ with the drugs regulator and the European Commission.
Europeans could have access to the first doses of a Covid-19 vaccine within weeks under an accelerated pandemic drug-approval process at the EMA, according to Ms Cooke.
Oxford/AstraZeneca announced yesterday it had a vaccine with effectiveness up to 90pc, depending on dosage.
The possibility that four Covid-19 vaccines could be available in the coming months offers the chance of more widespread vaccination outside of just at-risk groups by next spring.
Professor Luke O' Neill, an expert in immunology from Trinity College, Dublin, was speaking after Oxford-Astra Zeneca scientists said its jab, if given in two doses, is up to 90pc effective.
It follows results from pharma giants Pfizer-BioNTech and Moderna which may get regulatory approval next month.
Prof O'Neill said another drug company Johnson and Johnson is also due to announce results, holding out the possibility that we will have four vaccines.
He said once high-risk groups are vaccinated, more widespread availability may be possible from March depending on how many doses the companies can produce.
"If Johnson and Johnson come in and they are making three billion (doses), it will push it forward," he told The Pat Kenny Show in Newstalk.
Ireland is in line for around three to four million doses under a European Commission agreement. One of the dosing patterns used by the scientists suggested 90pc effectiveness if one half dose is given followed by a full dose.
Another dosing pattern showed 62pc efficacy when one full dose is given followed by another full dose.